A centrifugal separator is adapted to centrifugal separation of at least a first component and a second component from a supplied medium. The supplied medium may be in liquid or gas phase and may contain various types of particulate material.
Achieving correct lubrication of the bearing or bearings which support the rotor of a centrifugal separator is a problem. If a bearing receives too much lubricant, the friction and thus the temperature in the bearing increases, and if the bearing receives too little lubricant there is risk of the bearing seizing.
As a simple way of providing one or more bearings in a centrifugal separator with correct lubrication and cooling a mist of lubricant can be used. For it to be possible for such a lubricant mist to be conveyed to a bearing and used for achieving correct lubrication of that bearing, the lubricant mist should not comprise drops larger than a certain size. A lubricant mist which comprises drops larger than a certain size risks over lubricating the bearing. At the same time, such a lubricant mist will not be stable enough to withstand being conveyed to a remote lubrication point such as a bearing, since large particles, owing to their mass, are more influenced by gravity and inertia forces, causing them to hit and moisten various surfaces in the separator before they reach the desired lubrication point. The generation of lubricant mist also needs to be adaptable to the centrifugal separator's operating conditions in order to provide correct lubrication of one or more bearings during varying operating conditions.
EP 0756897 A1 (Veronesi Separatori S.p.A) refers to a centrifugal separator of the above-mentioned type, comprising an upper and a lower bearing on a rotating spindle and a device for generating lubricant mist. Above the lower bearing, the spindle is provided with a disc having apertures which during rotation draw lubricant up through stationary ducts in contact with an oil pan situated below. Lubricant drawn up through the ducts is projected by the disc in the form of drops or lubricant mist. The lubricant mist thereafter lubricates the lower bearing via further apertures in the rotating disc.
SE 521030 C2 (Alfa Laval Corporate AB) refers to a lubricant supply device in a centrifugal separator comprising a spindle with a longitudinal duct which has an orifice immersed in a pan of lubricant and adapted to conveying a flow of lubricant through the duct. The duct comprises a distribution means which divides off a selected amount of the flow for conveying to and through a lower bearing and also upwards to an upper bearing in the form of lubricant mist.